Question

1.) The Ka of dichloroacetic acid (C2H2Cl2O2) is 3.32x10^-2. Determine the concentration of all species present at equilibrium in a 0.100M C2H2Cl2O2 solution.

2.) what is the pH of the 0.100 M C2H2Cl2O2 solution?

Answer 1

1) C2H2Cl2O2 -------> C2HCl2O2- + H+

0.1                             0                   0

0.1-x                          x                  x

Ka = [C2HCl2O2-][H+]/[C2H2Cl2O2]

3.32*10^-2 = x^2/(0.1-x)

x = 0.0434

[C2HCl2O2-] = [H+] = 0.0434 M

[C2H2Cl2O2] = 0.1 - 0 0434 = 0.0566 M

2) pH = -log[H+] = -log(0.0434) = 1.36